Endokrinologie最新文献

Thyrotropin Releasing Hormone (TRH) shows the obvious and long-durated stimulation to the neonatal thyroid tissue through the pituitary. The sequential changes of serum thyroglobulin (Tg) levels and light and ultrastructural change in the cells of the thyroid gland were studied after TRH injection into neonatal rats. TRH injection induced a rapid increase of the colloid droplets in the thyroid follicular cells followed by a slow increase in serum Tg levels. Ultrastructurally, although marked surface activities consisting of formation of pseudopods and colloid droplets were observed after TRH injection, luminal colloid did not appear to go across the intercellular space between the thyroid follicular cells.

1. In male rats under urethane/chloralose anaesthesia the pituitary gland was exposed by transpharyngeal approach. The following methods were applied: (a) posterior pituitary lobe incubation in situ with the anterior lobe removed and the posterior lobe elevated so that only the vessels between the lobe and the meninges are broken, and continuous exchange of the incubation fluid; (b) removal of the entire pituitary and continuous exchange of the fluid washing the cut proximal end of the pituitary stalk. 2. 20 to 30-min samples of incubation or washing fluid were collected for 3-5 hrs and oxytocin was assayed according to Van Dongen and Hays (1966). 3. Preganglionic stimulation of the superior cervical ganglion caused significant increase (ca. 25 times) of oxytocin release from the posterior pituitary lobe. 4. Preganglionic stimulation of the superior cervical ganglion did not alter oxytocin content in the fluid washing the cut proximal end of the pituitary stalk. 5. The sympathetic neurons of the superior cervical ganglia could evoked oxytocin release from the neurohypophysis but did not change its outflow from the hypothalamus to the neurohypophysis.

In 9 patients with gonadal dysgenesis (karyotype 45/XO), the responsiveness of thyreotropic cells of the pituitary was investigated by stimulation with thyreotropin-releasing hormone (TRH). Both after hormone substitution in the form of sequential therapy (mestranol/mestranol-chlormadinone acetate) and after the end of therapy the investigations were repeated. TSH was determined by RIA, total thyroxine and binding capacity of thyroxine binding globuline (TBC-index) by protein binding assay. The free thyroxine index (FT4-index) was calculated. The results show that the hypothalamic-pituitary unit in patients with gonadal dysgenesis reacts in a similar manner as in normal female subjects.

In a 12 years old patient with asymmetric mixed gonadal dysgenesis (karyotype 45, XO/46,XY) a stimulation test with arginine, gonadotropin-releasing hormone (GRH) and thyreotropin-releasing hormone (TRH) was performed before and after exstirpation of the gonads as well as after application of sex steroids. FSH, LH, PRL, HGH, TSH, testosterone and oestradiol were determined by radioimmunoassay. The results show an intact hypothalamo-pituitary axis which reacts with a normal negative feedback with respect to the secretion of gonadotropins after application of sex steroids.

Cortisol, insulin, somatotropin, thyreotropin, thyroxine, triiodothyronine, testosterone, aldosterone, c-AMP, c-GMP, prostaglandins (PGF1-x, PGF2-x, PGA + E), and renin concentrations in serum or plasma of the venous blood of the third international crew of the scientific orbital complex of "Soyuz 29 - Salyut 6 - Soyuz 31" were determined following the 7-day space flight. The increased activity of the renin-angiotensin-aldosterone system before the flight as well as variations in the pressor/depressor prostaglandin ratios indicate an increased strain during the pre-flight period. During the first stage of the post-flight period some parameters were changed due to the landing process and the returning to earth gravity. The associated physical load and the onset of reactions for enhancement of the orthostatic tolerance resulted in an increase of cyclic nucleotid and thyroxine concentrations. The relatively higher levels of the pressor PGs of group F in comparison with the prostaglandins A + E could be evaluated as a compensatory reaction for enhancement of the orthostatic tolerance. The cortisol and STH concentrations increased with growing motor activity. The variations seen after the 7-day space flight were essentially within the reference areas. It may be assumed that the readaptation was not yet totally accomplished by the 8th day after landing.

To determine if oxytocin and estradiol were effected by pelvic neurectomy (PN), utero-ovarian vein blood was collected from PN rats during the preparturient period and assayed for these hormones. Radioimmunoassayable oxytocin levels were not significantly different in any groups of sham operated (S) or PN animals on days 21 and 22 or PN animals on days 23 and 24. Estradiol (E2) levels rose significantly on day 22 in S animals but there was no significant change in E2 in PN rats throughout the time period studied, although E2 levels were generally high. These results indicate that the blocked parturition characteristic of PN animals cannot be attributed to altered oxytocin levels. The lack of a significant E2 surge on day 22 in PN rats may contribute to the failure of utero-ovarian vein prostaglandin F levels to rise in these animals during the preparturient period.

A direct method has been described which enables a specific assay of progesterone without extraction in human plasma or in other material containing corticosteroid binding globulin (CBG). When using 20 microliter of plasma per tube, a sensitivity of 6 pg/tube, or 0.3 ng/ml can be achieved. The precision and accuracy are comparable to those observed in methods involving extraction. The described method is particularly suitable for routine assays.